Winter 2014-2015 Pattern Discussion Thread III

[Cold Rain]

Cold rain, I don't see how with not a neg ao or nao we see any sustained cold or winter storm threat that looks likely. The thing I'm confused about is why aren't the ao and nao going neg? What's main culprit and how likely is it to change

Hey bud, in answer to you last question, if you ask 10 different people, you'll get 10 different answers as to why neither the AO nor NAO has been negative. Same thing with what's likely to change it. Nobody really knows. There was almost unanimous agreement that blocking was going to be the theme, heading into the winter. Most expected it to have already shown up, although some fairly digigent history rewriting is going on now.

As far as cold and snow goes, you absolutely 100% do NOT need the AO or NAO to be negative to get either. The big -EPO drove the pattern last year.

I like to think of winter weather in the SE in the context of the old threading the needle metaphor.

Most patterns, not all, but most, will allow for perfect timing to create a winter storm. The thread is big and the eye of the needle is small, but it can still be done, if things work out just right.

However, well-placed blocking can easily make the thread smaller and the eye of the needle bigger. That's what we want to see. Unfortunately, we don't....not for at least the next 10 days. It's hard to get a winter storm in the SE. That's why I'm so in favor of a west-based -NAO, with some ridging out west and a suppressed storm track. It'll make it easier for us to score.

Read HKY's post. That's what's most likely to happen until when/if a more favorable pattern sets up. In other words, we can still score. But we're starting on our own 20 yard line with 10 men on the field against a fast, tough defense.

I'm not negative on the rest of the winter. Just bummed because all of December and likely the 1st half of Jan will have offered very little in the way of even anything to track...cold shot notwithstanding.

[NCSNOW]

Pack that mjo forecast looks very promising. From Larry research phase 7 and 8 and entering cod from those phases is all you can ask for. 2 models look like they may come out of cod in phase 5 or 6 if they went out in time far enough but the other 2 come out of cod right back into phase 7. Going into cod from 7 or 8 is golden and they all predict that. Thanks for posting link.

[GaWx]

Think about it this way. We're about to get a strong cold shot during MJO phase 5 outside of the COD, the warmest phase by far! It may even challenge record cold for non-COD 5 (back to 1975). If we can get that during such a warm phase, what might we get if we get a favorable COD MJO into 6-7-8-1-2 in the last half of Jan whether or not we finally get a solid -NAO/AO?

[NorthernUpstateSC]

Just last week most models were not giving to much hope on any cold weather anytime soon. Now just a few days later we have what appears to be a major artic outbreak heading this way and it appears some are not too happy about this. Oh it is just going to torch after this and if that is the case bring on spring. Blah, Blah, Blah, come on people lets get real.... The idea of a wall to wall cold that was talked about by some in november in the south is completely unrealistic and if that is what you want then you need to move to international falls. That ain't happening here unless you are 3500 or more feet above sea level in western nc and even there it warms up.

 

I am a transplant for up north and have lived in the south for 38 years and only two times that I can remember it staying cold for a long period of time (30 days or longer). That was in Dec.1989 and Jan. 1988, in 1988 this was because of the 16 inches of snow we got that first week set a record in the upstate of sc for the number of days in a row that temps at night got into the teens or lower. A typical winter in this area of the country is a few days of cold followed by a warm up to normal or above and if you are lucky enough another shot of cold air comes in a few days later. The transient shots of cold air some complain about is just a way of live down here in the south. How about we enjoy this cold coming next week and then see if we can thread the needle and get a nice winter storm for most. The negativity that is on here sometimes can be ridiculous.

[HKY_WX]

HKY,

1) Based on the recent major failures of the Euro ens 11-15 as well as Euro weeklies for 1/5-11 (see my post from a few days ago), I'd take any 11-15 EPS progs with a huge grain right now.

2) Keeping that in mind and considering other factors I noted earlier, the lack of blocking to this point is far from being anything close to a signal that the last half of Jan can't be quite memorable.

3) Phasing is not at all needed for a big and widespread SE winter storm as per my posts showing that most of the big SE SN/ IP were produced by WEAK Miller A's while in the Gulf. Strong storms in the GOM tend to not track as far south and bring up too much warm air for most of the SE.

edited

Well I take any model for any time period with a grain of salt. I agree anything is possible, we could have a storm with a lack of blocking, especially with the +PNA pattern. I have done research showing a positive PDO/PNA pattern can be just as important to a winter storm in the south in certain situations. Specifically ice, as it allows cold core HP's enter the picture like we've seen this past fall and into winter.

 

That said, there's no doubt blocking near Greenland (especially west based) increases the chances for winter weather (specifically snow) and prolonged below average temperatures. Climatically the weather is also slightly different for parts of NC than the rest of the south(mirrors more of the southern mid-atlantic). The NC big dogs of the recent past (jan 96, feb 04, dec 09, dec 10, etc, all weak SLP's) resulted from a classically good pattern (50/50 low, blocking, phasing/cutoff lows, etc) and they all slammed NC. So some of my posts have a hint of IMBY-nc centric status.

 

Looking ahead I haven't seen anything that increases the chances of the AO or NAO going negative in January. The MJO is a highly volatile index and predicting SSW events is very unreliable as well. I am hoping just based on weak-nino climo we'll get a system this winter and I'm hoping the AO will change later in winter. February and March can make you forget the rest of winter pretty quickly if they work out. As of now that's hope. I hope i date a super model next week too. 

[GaWx]

HKY,

Thanks for clarifying. Yeah, none of the four storms you listed were anything close to major at ATL/most of N GA. They were more NC concentrated. I was thinking more widespread, including NC/GA/SC/AL/TN.

[packbacker]

Well I take any model for any time period with a grain of salt. I agree anything is possible, we could have a storm with a lack of blocking, especially with the +PNA pattern. I have done research that a positive PDO/PNA pattern can be just as important to a winter storm in the south in certain situations. Specifically ice, as it allows cold core HP's enter the picture like we've seen this past fall and into winter.

 

That said, there's no doubt blocking near Greenland (especially west based) increases the chances for winter weather (specifically snow) and prolonged below average temperatures. Climatically the weather is also slightly different for parts of NC than the rest of the south(mirrors more of the southern mid-atlantic). The NC big dogs of the recent past (jan 96, feb 04, dec 09, dec 10, etc, all weak SLP's) resulted from a classically good pattern (50/50 low, blocking, phasing/cutoff lows, etc) and they all slammed NC. So some of my posts have a hint of IMBY-nc centric status.

 

Looking ahead I haven't seen anything that increases the chances of the AO or NAO going negative in January. The MJO is a highly volatile index and predicting SSW events is very unreliable as well. I am hoping just based on weak-nino climo we'll get a system this winter and I'm hoping the AO will change later in winter. February and March can make you forget the rest of winter pretty quickly if they work out. As of now that's hope. I hope i date a super model next week too.

I have a feeling we are going to look back on this winter and say it was fairly evident from Dec and early Jan that blocking wasn't going to materialize. None of the snowy analogs had this lack of blocking. 2005/2007 did develop a -AO in mid/late Jan and into Feb. I guess that's something but those were not great winters, atleast here.

Also, the clipper next week may give the NE 2-3" but this winter has been so bad for so many places for snow. That's a red flag too.

[GaWx]

I have a feeling we are going to look back on this winter and say it was fairly evident from Dec and early Jan that blocking wasn't going to materialize. None of the snowy analogs had this lack of blocking. 2005/2007 did develop a -AO in mid/late Jan and into Feb. I guess that's something but those were not great winters, atleast here.

Also, the clipper next week may give the NE 2-3" but this winter has been so bad for so many places for snow. That's a red flag too.

Pack,

Many of the great SE winters for wintry precip had avg to below avg SN in the NE. Getting above avg SN in the NE may even be partially negatively correlated to above avg SN in the SE (though I don't know) though less so up your way.

The factors that produce above avg NE seasonal SN and those that do the same in the SE are not at all one in the same though there is probably overlap of a few factors.

Some of the greatest SE Miller A storms were suppressed/weak enough to largely avoid the NE.

[Webberweather53]

Think about it this way. We're about to get a strong cold shot during MJO phase 5 outside of the COD, the warmest phase by far! It may even challenge record cold for non-COD 5 (back to 1975). If we can get that during such a warm phase, what might we get if we get a favorable COD MJO into 6-7-8-1-2 in the last half of Jan whether or not we finally get a solid -NAO/AO?

 

This is exactly what I've been contemplating. We virtually have the most unfavorable equatorial forcing currently at hand yet we aren't torching, that's a red flag...

[HKY_WX]

HKY,

Thanks for clarifying. Yeah, none of the four storms you listed were anything close to major at ATL/most of N GA. They were more NC concentrated. I was thinking more widespread, including NC/GA/SC/AL/TN.

 

no prob

 

I have a feeling we are going to look back on this winter and say it was fairly evident from Dec and early Jan that blocking wasn't going to materialize. None of the snowy analogs had this lack of blocking. 2005/2007 did develop a -AO in mid/late Jan and into Feb. I guess that's something but those were not great winters, atleast here.

Also, the clipper next week may give the NE 2-3" but this winter has been so bad for so many places for snow. That's a red flag too.

We'll see, hoping things change. I don't see this being a torch of a winter, b/c the overall north american pattern really isn't horrible. Just not what you want to see for routine snow chances in the eastern CONUS.

[deltadog03]

Hmmm...Don't look now, but GFS might** have some over-running frozen or freezing trying to push into AL, and GA by early next SAT

[deltadog03]

IMHO this will REALLY have to be watched.  EURO kind of hints at it, but not really.  Either way it will be weak, and a slowly warming Arctic airmass, but it should scour out that quickly.  Could be fun with that next weekend.

[BullCityWx]

Hmmm...Don't look now, but GFS might** have some over-running frozen or freezing trying to push into AL, and GA by early next SAT

 

Ptypes showing light snow up near Atlanta. 

[BullCityWx]

Also, there's snow just offshore around JAX at hour 126. 

[GaWx]

In addition to the fun already mentioned, the 228 hour GFS is already setting up for still another run of a strong SE cold shot mid month as well as a close call around 1/12, Let's see how the rest of the run goes.

[burgertime]

IMHO this will REALLY have to be watched.  EURO kind of hints at it, but not really.  Either way it will be weak, and a slowly warming Arctic airmass, but it should scour out that quickly.  Could be fun with that next weekend.

 

GFS PARA is close to something well in that time frame as well. 

[burgertime]

I guess I have become pretty pessimistic, but won't this be moisture chasing retreating cold and we have to hope it comes in sooner than being modeled or the cold hangs on a little longer? Is it just frontal passage with a little precip ahead of next front?

 

No. You have a descent CAD setup with a weak low in the gulf. It doesn't do much in the end but it's showing that the potential is there. 

[BullCityWx]

Even if we only get a few hundreths to a tenth of an inch, you're going to have a ground that is frozen solid. It wont take much to cause a mess. 

[burgertime]

GFS: holy sheet for mid month !!

 

Yep big time cold. I strongly suspect we get in a repeating pattern. Again just will be a matter of timing. 

[GaWx]

The cold shot on this GFS mid month is actually more impressive than next week's very cold shot! Before you laugh about it being 12-4 days out, the GFS has been consistently showing some degree of an Arctic shot then.

The negativity at this bb is becoming laughable in light of all of this.

[burgertime]

The cold shot on this GFS mid month is actually more impressive than next week's very cold shot! Before you laugh about it being 12-4 days out, the GFS has been consistently showing some degree of an Arctic shot then.

The negativity at this bb is becoming laughable in light of all of this.

 

Yea a few things with that. I noticed that GFS had -30's showing up in Canada in the LR....same today. I really like that. 0 degree line makes it all the way into TN. We need those -30's rotating down into Canada. 

[GaWx]

Yea a few things with that. I noticed that GFS had -30's showing up in Canada in the LR....same today. I really like that. 0 degree line makes it all the way into TN. We need those -30's rotating down into Canada.

Two major Arctic plunges just a week apart would not exactly be ordinary. IF that 2nd plunge were to verify and the rest of the month were to at least be on the chilly side (I'm strongly suspecting this ), this month would have a shot at ending up quite cold in the SE and one of the classic very cold Jan's even despite the slow start. That's what the recently maligned analogs have been suggesting.

[burgertime]

Two major Arctic plunges just a week apart would not exactly be ordinary. IF that 2nd plunge were to verify and the rest of the month were to at least be on the chilly side (I'm strongly suspecting this ), this month would have a shot at ending up quite cold in the SE and one of the classic very cold Jan's.

 

GFS PARA looks fantastic in the LR. Just a repeating pattern of dropping the PV down and bringing in major cold. 

[GaWx]

GFS PARA looks fantastic in the LR. Just a repeating pattern of dropping the PV down and bringing in major cold.

The recently maligned cold Jan/ Feb ENSO/+PDO analogs have been insisting on a cold rest of winter after December. Despite the slow start to Jan, I dare say that these analogs are still very much in the game even with blocking still in Q. This may very well end up as a delayed (~ a week) rather than denied situation. If we also get the favorable MJO, look out below!

[deltadog03]

Even if we only get a few hundreths to a tenth of an inch, you're going to have a ground that is frozen solid. It wont take much to cause a mess. 

BINGO!!!!  and to be honest, under a .25" of liquid would make this even worse right now, IMHO...The ground will most DEF be frozen.

[metalicwx366]

The recently maligned cold Jan/ Feb ENSO/+PDO analogs have been insisting on a cold rest of winter after December. Despite the slow start to Jan, I dare say that these analogs are still very much in the game even with blocking still in Q. This may very well end up as a delayed (~ a week) rather than denied situation. If we also get the favorable MJO, look out below!

Check out the deep south snow storm around the 300 hour mark!

[GaWx]

Are the Euro weeklies about to also blow chunks with their mild (at 2 meters )

mid to late Jan fcast? 1/5-11 is about to verify as a major failure . Could 1/12-18 be far behind?

Edit: Metal, AYS SN ftw !

[NC_hailstorm]

Marginal severe weather threat tomorrow before the plunge.

 

...THERE IS A MRGL RISK OF SVR TSTMS FOR PORTIONS OF CENTRAL AND
   EASTERN GA...SC/NC TO SOUTHEAST VA...

[Wow]

GFS and GFS Para both pointing toward a -NAO (!) after Jan 15.  I forgot what one looks like it's been so long!

[Srain]

Folks, this upcoming cold shot looks to have some legs. We are expecting freezing temperatures all the way to the Middle and Upper Texas Coast into Coastal Louisiana Thursday morning. The wild card is an approaching Western upper air disturbance on Wednesday with some potential of a Coastal trough developing later next week. That would likely impact the sensible weather for you folks in the SE Region.

 

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1057 AM EST SAT JAN 03 2015

VALID 12Z TUE JAN 06 2015 - 12Z SAT JAN 10 2015

...COLD BLAST TO MOVE THROUGH THE CENTRAL/EASTERN/SOUTHERN STATES
MIDWEEK...


...OVERVIEW...

HIGHLY-AMPLIFIED FLOW PATTERN ACROSS NORTH AMERICA WILL PRODUCE
BELOW AVERAGE TEMPERATURES FOR THE MAJORITY OF THE COUNTRY EAST OF
THE ROCKIES NEXT WEEK. ALONG THE WEST COAST OF NORTH AMERICA... AN
UPPER-LEVEL RIDGE WILL PREVAIL DURING THE FIRST HALF OF THE PERIOD
BEFORE A SERIES OF PACIFIC SYSTEMS WILL FIND A WEAKNESS IN THE
SOUTHERN HALF OF THE RIDGE AND MOVE INTO THE PAC NW AND PAST THE
CONTINENTAL DIVIDE.


...MODEL PREFERENCES...

ENSEMBLES WERE GENERALLY IN GOOD AGREEMENT THROUGH THE END OF NEXT
WEEK THANKS TO A FAIRLY PREDICTABLE AMPLIFIED PATTERN. A BLEND OF
THE 06Z PARALLEL GFS AND 00Z ECMWF/ECENS MEAN OFFERED A GOOD
STARTING POINT TO THE FORECAST. RECENT 00Z/06Z OPERATIONAL GFS
RUNS SEEMED TO SUFFER FROM CONTINUITY ISSUES OVER ALASKA AND THE
EASTERN PACIFIC... MAKING THEIR USE LIMITED IN THE WESTERN DOMAIN.
FARTHER EAST... STRENGTH/LOCATION OF IMPRESSIVE SFC HIGH PRESSURE
WAS THE FORECAST CHALLENGE -- IMPACTING THE TEMPERATURE FORECAST.
NEAR 1060MB HIGH PRESSURE IS FORECAST BY THE MODELS WHICH WOULD
APPROACH OR EXCEED MONTHLY MAXIMUM VALUES FOR THE HIGH PLAINS.


...SENSIBLE WEATHER HIGHLIGHTS...

ON TUESDAY THE CLIPPER SYSTEM IS EXPECTED TO GENERATE A SWATH OF
SNOWFALL FROM THE MIDWEST TO THE UPPER OHIO VALLEY BEFORE EXITING
THE NORTHEAST ON WEDNESDAY. IN ITS WAKE... THE DEPTH OF THE COLD
AIR SUPPORTS LAKE-EFFECT SNOWS FOR THE GREAT LAKES AND ALONG THE
SPINE OF THE APPALACHIANS INTO NEW ENGLAND FOR MUCH OF THE MEDIUM
RANGE PERIOD. CORE OF 850 TEMP ANOMALIES SHOULD SPLIT E-W... ONE
CHUNK MOVING THROUGH THE OHIO VALLEY INTO THE SOUTHEAST AND THE
OTHER OVER TEXAS -- STANDARDIZED ANOMALIES IN THE -2 TO -3.5 SIGMA
RANGE WILL SUPPORT LOWS NEAR FREEZING TO THE GULF COAST.

WITH THE CANADIAN HIGH MOVING SOUTHEASTWARD MIDWEEK... HIGH AND
LOW TEMPERATURES WILL BE A GOOD 15-30F BELOW AVERAGE IN THE
NORTHERN PLAINS AND THEN SPREAD EASTWARD AND SOUTHWARD AS THE
STRONG HIGH SINKS INTO THE LOWER MS VALLEY. MANY LOCATIONS WILL
EXPERIENCE THE COLDEST AIR OF THE SEASON BY 10-15F.

IN CONTRAST... TEMPERATURES IN THE WEST WILL BE ABOUT 10-15F ABOVE
AVERAGE... WITH THE EXCEPTIONS BEING IN THE SHELTERED VALLEYS OF
THE GREAT BASIN AND CENTRAL ROCKIES WHERE STRONG INVERSIONS WILL
LIMIT THE OTHERWISE BROAD-SCALE WARMUP. PRECIPITATION WILL BE
LIMITED TO THE PAC NW LATER IN THE WEEK WHILE CALIFORNIA AND THE
DESERT SW SHOULD STAY DRY.


FRACASSO/VOJTESAK